Process of recovering potash salts.



A. ALBERTI. PROCESS OF REGOVERING POTASH SALTS.

APPLICATION FILED MAY 13. 1909.

957,295.. Patented May 10, 1910.

Au GUSTOALBERTB,

Attemajy.

- \NVENTOR,

AUGUSTO ALBERTI, or ROME, ITALY.

' rnocnss 0F nncovnnme rorasrr SALTS.

957,295, Specification of Letters Patent. Patented lw 1(1 1191(1 Application filed May 13, 1909. Serial No. 495,580.

To all whom it may concern.

Be it known that I, Aoousro ALBERTI, the tartrate of calcium.

chemist a subject of the Kin of Italy 1 residing in the city of Rome, Kingdom of i QtHGO+Ca(OH)ZTOtHtOGCalQI'LO' Italy, have invented certain new and useful Thus the tartrate of calcium While the potassium salts remain in the Improvements in Processes of Recovering l mother-lye. The mother-lye is separated Potash Salt, of which the following is a from the tartrate of calcium by decantation,

precipitates,

specification.

The subject matter of the present invenand the tartrate ofcalcium Washed With Water until the potassium salts arev elimition is a process for recovery of the potassium salts (chlorids and sulfates) contained nated, and afterward it is treated with sulfuric acid, in order to free it from the tar- 1n the residual Water obtained from the manufacture of tartaric acid after the tartaric acid. The mother-lye of the tartrate trate of calcium has been precipitated by milk of lime. It is Well known that, on account of the large quantity of organic substances which the said residual Waters contain, the direct concentration of the same is not practically possible,'so that the potassium salts contained therein are entirely lost. According to the present invention the recovery of the potassium salts is rendered possible and industrially profitable. by causing the said residual Water to undergo a preliminary treatment with hypochlorous acid, supplied by the hypochlorite of calcium or chlorin in the presence of a base, for the purpose of effecting the oxidation of the larger part of the interfering organic substances, and for the purpose of facilitating thereby the concentration 'of the Water and the recovery of the salts by means of crystallization.

" The complete process for the treatment and has an acid reaction due to the presence of tartaric acid, of other organic acids and of metallic acid salts, The same is treated With lime until it shows a basic reaction, and after filtration it is submittedto the described, for thepurpose of extracting the potassium salts. The expression motherlye of tartrate of calcium. is to be understood as designating the residual or refuse Water remaining after the precipitation of organic substances containing the tartaric acid by the limemilk, as hereinbcfore d scribed.

The quantity of.the potassium salts contained in the mother-lye of the tartrate of calcium depends upon the strength of the tartaric solutions which are obtained in the first phases of manufacture of the tartaric acid; the potassium salts are recovered by of the crude tartaric substances is fully excrystallization, for which purpose the plained' in the following specification. mother lye must be sub ected to a suitable The ground tartaric substances (Wine lye, concentration.

. The essential feature of the process consists in the oxidation of nearly all the organic substances contained in the motherlye of the tartrate of calcium.

During the process of oxidation the water is purified, the solution becomes concentrated, the potassium salts easily crystallize out, and there is no formation of poorly con ducting scale on the heating surfaces. For this purpose, advantagevisv taken. of the oxiraw cream of tartar, etc? reduced to mud by the boiling action 0 bubbling steam, and thereafter disintegrated by cooking in an autoclave, are treat.ed With hydrochloric or sulfuric acid. The bitartrate of potassium contained in these substances reacts with the acids, as-follows:

The muddy liquid thus obtained contains dizing action of the hypochlorous acid tartaric acid and a salt of potassium, chlorid (H010). In practice, commercial (-hlorid or sulfate; the mud is separated by filtraof lime (CaOCh) is used,-the active portion tion from. the tartaric so ution containing of which is the h *poohlorite of calcium, the potassium salt, and thefiltered liquor Ca (001 Even c lOI'lIl can be employed is treated with limemilk, in order to obtain process hereinafter.

the tartrate of calcium from the solution of calcium thus obtained contains dissolved 25 up to about by causing-the same to react on the mother-l lye of the tartrate of calcium in the presence of a base (lime). The reaction 1s:

water contains sulfate .of potassium, sulfate of calcium is also formed during the treat- .ment with the hypochlorite, and the sulfate of potassium is changed into chlo'rid of fp0 tassium. B means of filtration the sul ate and the car onate of calcium are separated,

hydrochloric acid is added until the filtered liquid is neutralized; it is then concentrated,

in order to extract the potassium salts by crystallization. If the purified water contains chlorid of potassium, it is concentrated 35 to 40 Bzium, whereby crys-- talli-zcd chlorid of potassium is obtained.

In the annexed drawing the arrangementof a plant for commercially carryingout the process isshown diagrammatically by way of example. After having been first treated with lime and filtered, the mother-lye of the tartrate ef calcium resulting from the manufacture of tartaric acid and which contains the po-- tassium' salts, is gathered in the tank 1.

This mother-lye, by means of pipes, is conveyed to tanks 2 of sandstone or ,other suitable material destined for the treatment with the hydrochlorite of calcium. For this treat- 40 ment there is formed in the sandstone watering device 3, a mixture of hypochlorite of lime (CaOCl and liquid from the tank 1. 'lhereupon'the mixture is caused to droplittle by little into the tanks 2, where the .hypochlorite of calcium reacts with the oxidizable organic substances contained in the mother-lye of the tartrate of calcium. The liquid is kept in continuous motion during several hours by means of mechanical stir,-

ring devices. The quantity of hypochlorite to be added to the waten to be purified is determined each time by preliminary test with permanganate of potassium. If the water contained in the tanks 2, is discolored, it is, filtered in the tank 42. If the purified water contains sulfate of calcium, sulfate of calcium with the carbonate of calcium remains on the filter. After that the concentration is started. This concentration is .talns densed from Wall of the tubes, while the-steam pr apparatus is brought about by means of a vacuum evaporator of any kind. Excellent results are, for -1nstance, obtained with the Kcstner evaporaters, of which the drawing shows a type well fitted for this process. For the sake of as simplicity, the drawing represents asingle camels acting" rather than amultiple acting evaporator.- The apparatus works on the cycle 111C1- ple. The water of the tank 4, who conthe potassium salts, by means of a pipe 5, is sucked up into the system of vertical' tubes contained in the body of the vacuum room and surrounded by the steam which enters through the pipe 6, in the casing 7, of the apparatus. he wate r conthe steam passes out through the pi e 8. The water to be concentrated starts boiling at the base of the systemof vertical tubes, and through the steam produced it is drawn in thin layers alon the uced by the evaporation fills the central part of the tubes. The liquid and'the steam, when they are leaving the system of tubes, meet the centrifu al bafile designed to entirely separate the liquid from the steam; the concentrated liquid, through the lateral pipe 9,

flows into the vat 10, in the present. instance containing liquid, or into the next box, if the evaporator is multiple acting, while the steam flows into the casing of the next box or into a barometric condenser 11, if the evaporator is single acting. i

The concentrated mother-lye leaving the gathered in the tank- 10. Here 'theretakes place a deposit of crystals of potassium salts, which can easily be recovered. After the tank 10 has been'filled, the excess of solution saturated with potassium salts is discharged through an overflow into 0 t e tank 4, where the same becomes mixed with the other purified water and the cycle of evaporation commences a ain.

If the potassium salts which are obtained.

bythis process are'essentially formed of the 5 chlorid, the'residual water, which is caused to flow into the tank 4, ismore and more enriched in chlorid of calcium produced by the hypochlorite of lime. \Vhen the water has reached the density of 85 to -l0 Baum, it should be taken out of the cycle and it'can again be put into'the reaction tanks-for the manufacture of tartaric acid, as has previously been stated.

I claim:

Process of extracting potassium salts from the refuse liquor of the manufacture of tar: taric acid, which consists in oxidizing the organicsubstances contained therein by adding to said liquor substances capable of de: veloping hypochlorous acid, concentrating the purified mother-lye in a vacuum and crystallizing out the potassium salts.

In testimony whereof, I have signed my name to this specification in the presence of two subscribing witnesses.

' AUGUSTO ALB ERT'I.

lVitnesses LETTERN Lansonn'r'rm, An'romno LABscEer-m. 

